Percussion rock drill



Feb. 5, 1952 E. CRAIG PERCUSSION ROCK DRILL 2 SHEETSSHEET 1 Filed June2, 1950 Feb. 5, 1952 7 E. CRAIG 2,584,330

PERCUSSION ROCK DRILL Filed June 2, 1950 I 2 SHEETS-SHEET 2 [n n enzor''Ernesf Craig Patented Feb. 5, 1952 PERCUSSION ROCK DRILL Ernest CraigLakefie'ld, Ontario, Canada Application June 2, 1 Seri l N 1:65.63

. 5' Claims.

This invention relates to improvements in percussion rock drills of thetype in. which a rapidly rotating hammer is, utilized to. strike thedrill shank or a tappet interposed between, the drill shank and hammerto thereby effect. rapid 'vibratory reciprocation of the drill shank inthe direction of its length.

In the past such rotary percussion drills normally have the hammermounted on a rotor, which is rotated about its axis which is fixed inrelation to. the drill and the. hammer is movable relative the rotor tostrike the t'appet or steel and then recoil. 'In' some cases. thehammers are pivoted to the rotor and in some cases run on trackways, asfor example in my United- States Patent No. 2,392,233, issued January 1,1946..

Such drills are subject to several disadvantages. one particulardisadvantage is that the. blow delivered by the hammer is not by anymeans entirely in the direction of the length of the drill shank orsteel but has a relatively large. component of movement in a transversedirection due to the rotative motion of the rotorarid there isconsiderable slippage or dragging of the hammer over the steel infollowing the movement of the rotor, resulting in loss of efficiency andwearing.

Further, there is considerable recoil back to the rotor or trackwaywhere employed, due to bouncing of the hammers, resultin rapid wearingof the drill parts, discomfort to the operator and short life operationfor the drill.

The principal object of the present invention. is therefore to provideanimproved hammer action in which the rotary motion of the drill rotorwill be converted into hammer motion to now directed longitudinally ofthe steel while causing the hammer to subsequently lift. withoutdragging over the steel.

In a particular form of the, invention one or more cages are mounted ona driven rotor for rotation about an axis offset from the axis of therotor. A hammer element, is mounted in each cage to swing about. a pivotoffset from the axis of the cage, the cage being driven upon rotation 1he rotor throu h an ep cl i l gear fat the tappet. or steel sh nk roiite i to h path of the hammer with the hammermovin at impact with thetappet under centrifugal force resulting from the com osite motion oforbital translation and rotation of the cage essentially .in a directionaligned with the tappet.

Another feature of the invention resides in the provision for accuratelytiming the cage movee ment to deliver the correct hammer stroke.

deliver a positive accurately placed percussion f blow through to thesteel in the direction of its length, and to subsequently lift thehammer in the direction from which the hammer blow was Y delivered tothereby eliminate slippage or drag-p j 'ging of the hammer over thesteel to provide a more eflicient drill in which wear will be reduced toa minimum for long life operation.

Another important object is to relieve shock to the hammer supportingrotorjand'rotor' driva A further object is to provide adrlll having abalanced operation.

Still another object is to provide a percussion drill of efficient andeconomical construction.

The principal feature of the invention resides in constructing apercussionw drillemploying an epicycloidal wheel arrangementiorconvertih rotative motion into substantianypu're linear.reciprocating motion. to give. an efieptive' hammer Still anotherfeature resides in th rovision of a hammer constructed for optimumefiiciency in transferring its kinetic energy to the tappet or steel onimpact.

Referring to the accompanying drawings, Figure 1 is a vertical sectionalview on the line l-el of Figure 2 through a percussion'drill constructedin accordance with this invention. I

Figure 2 is a vertical sectional view taken through the drill at rightangles to Figure 1 on the linev 2 2 of Figure 1.

Figure 3 is a perspective view of the inner wheel or timing gear oi thedrill cage. t

Figure 4 is a perspective view of one form of hammer which may b3employed.

Figure 5 is a perspective view of the cage for a hammer of th t pe ofFigu e 4- Figure 6 is aperspe'ctive view of an alternative form of cageof a preferred form.

Figure 7 is a perspective view of the hammer to be used with the cage ofFigure 6.

Figure 8 is a perspective view of the cage gear for the c ge of- Fisu eigure Bis a vertical sectional view t ou h the case-of Figure 6 wi h theham r in la a d showing th relation f the as and hammer as the hamm r isd li e in its mpact blow to the ta pet.

With refer nce to the drawi gs the drill casing l is shown as a c rcularcasting formed h nal flanges}. and an axial y fiset ext 3 having acentra bore 01' pa sage 4 in whi h is slidably received a tappet orsteel shank to project within the casing.

Secured to the casing I are the closing face plates 5 and heldoutwardlyfrom the flanges 2 by their circular flanges 8 under theclamping action of the bolts 9.

Each of the face plates 6 is formed with a central journal boss II! inwhich is mounted a journal I I held in position by a plate I2.

Rotatably supported in each of the journals I I is a rotor member I3 inthe form of a flanged collar mounted on a hub I4 having a shaftextension I6 entered in the journal I I. These rotor members I3 areformed to receive journals I8 held in position by plates 20.

The journals I8 of the opposing rotor members I3 are axially aligned andjournalled therebetween are ca es 22 formed with axially aligned studshafts 23 received within the journals.

Mounted within the flange 8 of one of the face plates 6 is an internallytoothed ring gear 24, and mounted on bosses 25 formed on one face of thecages 22 concentric with its stud shaft 23 aregears or toothed wheels25' of annular form arranged to mesh with the ring gear 24.

The ring gear 24 is fixed and the gears 25' of the cages have a diametersubstantially one half that of the ring gear and are arranged on therotor members 53 to revolve about the centre of the internal gear whilemeshing therewith to form an epicycloidal wheel arrangement whereinmotion of points offset from the axes of the stud shafts 23 of the cagestowards the circumference of the gears 25' have a linear motion.

Each of the cages 22 is provided with a recess 26 opening inwardly fromthe periphery thereof, and inserted in each of these recesses is ahammer 21 which, in the form shown in Figure 4, has a shank portion 28,head 29, formed with a striking face 30.

The hammer 2! is pivoted on pin 3I to swing about an axis parallel tothe axis of the cage 22 in which it is mounted but offset towards theperiphery of the cage. The hammer 2! is permitted limited movementwithin the recess 26, and to accommodate this movement it is formed withthe guide grooves 32 into which project the stop ribs 33 formed on theinner faces of the cage recess 28 and of substantially lesser width thanthe grooves 32. I

As shown in Figure 1, the timing of the epicycloidal wheel as formed byinternal gear 24 and cage gear 25' is such as to bring the hammerstriking face 30 of each cage into position to strike the tappet orsteel 5 while moving essentially in the direction of the length of thetappet.

Operation In Figure 1 the direction of the rotor members I3 as driventhrough the shaft 2I is anti-clockwise. The rotors carry the cages 22bodily so that they are being bodily revolved about the axis of therotors and ring gear in an anticlockwise direction. The cages in turnare meshing with the ring gear 24 and being rotated thereby in oppositedirection to their bodily revolution. The direction of the rotation ofcages about their own axes is therefore clockwise and at twice the speedof the rotor due to the relationship of the cage and its gear 25' beingonehalf the diameter of the ring gear as explained, and thisrelationship converts the rotary motion of the cage and rotor intoessentially a reciprocal hammer blow directed longitudinally of 4 thetappet as hereinafter more particularly described.

The hammers 21 carried by the cage are urged outwardly of the centre ofthe rotor under centrifugal force. The hammer pivots move sub stantiallyon a diameter of the rotor or ring gear 24 and the timing of the gears24 and 25' are such that the hammers are positioned as they reach thesteel 5 as shown in Figure 1 to be moving clockwise about their pivotsat a speed in excess of the cages under centrifugal force with themotion component of the hammer heads at impact being substantiallyaligned with the axis of the tappet 5 to deliver the desired percussionblow.

After the impact the cages continue to rotate clockwise about their ownaxes while being revolved bodily anti-clockwise to effect a lifting ofthe hammer from the steel in a direction from which the hammer blow wasdelivered to prevent the hammer from being dragged past the steel as inprevious constructions. That is, at the instant of impact the hammer pin3|, due to the clockwise motion of the cage, is moving from a positionin retard of the tappet in relation to the direction of rotor movementinwardly of the rotor axis with the above noted result.

The hammer is designed to have sufficient weight to carry through tosome extent after the blow although the hammer must also be permitted tolift after the blow so that the drill will not vibrate excessively. andalso the hammer must be balanced so that the impact is a balanced blowon the steel.

It will be seen in Figure 1 that the hammer at impact is displaced toleave an air pocket 34 at its rear in relation to its direction ofimpact delivery and this air pocket may be utilized to cushion any liftof the hammer.

Figures 6 to 9 shown an alternative form of cage and hammer arrangement.The cage 35 of Figure 6 is formed with the shaft extensions 36,permitting it to be journalled between the rotor members I3 in alignedjournals I8. One face of the cage is formed with a concentric hub 31corresponding to the hub 25 on the cage 22 to receive the annular gear38 corresponding to the gear 25'.

The cage 35 is formed with a recess 39 diverging at 40 to form a widemouth extending for a considerable sector of the cage, with the cage atone side of the mouth being slotted to form the jaws 4|.

The hammer 42 is formed with a shank 43 and an enlarged head 44, fittingwithin the recess 39 and diverging mouth 40 respectively of the cage.The enlarged head 44 is formed with a striking base 45 of convex formwhich extends between the jaws M. The hammer is pivoted in position bythe pin 46 extending through the cage and into the groove 4'! formed inthe inner perimeter of the annular gear 38.

Figure 9 shows the position of the hammer and cage of Figures 6 to 8 atthe instant of impact, with the cage being rotated clockwise in thedirection of the arrow. It will be seen that the hammer is moving atimpact relative the cage to its position outwardly of the centre of thecage w as limited by the stop surface 48, and the blow will be under theepicycloidal arrangement in the direction of the tappet.

The lifting of the hammer after follow through under, the motion of thecage will eliminate any detrimental rebound action, and the hammer willdeliver a balanced effective percussion blow.

It will be understood that the rotor of the machine is heavy enough tocarry the cages through impact, therefore relieving shocks to the timinggears. Also the cages are of sufficient weight so that the hammer forceon the steel at impact is allowed to deliver its blow without liftingthe cages or carrying the shock from the hammer through the cages to thebody of the machine.

While the actual timing of the cages is determined by the ring gear 24and meshing cage gears, it is desirable that provision be made to adjustthis timing through the range of one tooth of the ring gear to deliverthe percussion blow in precisely the desired direction. To this end theinternal gear 24 is secured to the flanges 2 of the circular casing bymeans of the bolts 49 selectively engageable in the threaded orifices50.

It will be appreciated that a machine of the type described will aifordan extremely efiicient percussion drill in which the rotary drive motionis transferred into the desired straight line percussion blow; that sucha machine will be compact and rugged and will operate with the minimumof wear on the moving parts for long life operation. I

While the above description discloses a specific embodiment of myinvention it will be appreciated that variations and modifications maybe made within the scope of the appended claims. It will be noted thathereunder the term tappet is to include a separate tappet element on thedrill steel in the event such tappet element is not employed.

What I claim as my invention is:

1. In a percussion drill, a casing, an internally toothed gear ringmounted within said casing,

a cage revolvable about the centre of said gear and having a gearsubstantially one-half the diameter of said ring gear meshing with saidring gear, means for revolving said cage about the centre of said ringgear, a tappet reciprocally arranged to project within said casing, anda hammer carried by and movable relative to said cage, the timing ofsaid gears being arranged'to bring said hammer against said tappetmember while moving with substantially linear motion in a directionaligned with said tappet.

2. In a percussion drill, an outer internally I toothed ring gear and aninner gear substantially one-half the diameter of said ring gear mountedfor revolution around the axis of said ring gear and meshing therewithto form an epicycloidal wheel, means for revolving the inner gear aroundthe axis of said ring gear, a tappet member reciprocally arranged toproject within said casing, and a hammer carried by said inner gear tostrike said tappet.

3. In a percussion drill, a casing, an internally toothed ring gearmounted within said casing. a

rotor mounted to rotate on the axis of said ring gear, a cage ofsubstantially one-half the diameter of said ring gear eccentrically androtatably mounted on said rotor and provided with a gear of a diameterequal to cage diameter meshing with said ring gear, means for revolvingsaid rotor to drive said cage through said ring gear at twice rotorspeed, a hammer carried by'said cage and having a striking face movingin a substantially linear path under rotor and cage rotation, and atappet reciprocally arranged to project within said casing, the timingof said ring and cage gears being arranged to bring said hammer faceagainst said tappet while moving with substantially linear motion in thedirection of said tappet, said hammer being'mounted for movementrelative said cage upon striking said tappet.

4. In a percussion drill, a casing, an internally toothed ring gearmounted within said casing, a rotor mounted to rotate on the axis ofsaid ring gear, at least one cage of substantially onehalf the diameterof said ring gear eccentrically and rotatably mounted on said rotor andprovided with a gear of a diameter equal to cage diameter meshing withsaid ring gear, means for revolving said rotor to drive said cagethrough said ring gear at twice rotor speed, said cage having a slottherein opening to the periphery thereof, a hammer mounted in said slotfor limited movement relative said cage, and a tappet reciprocallyarranged to project within said casing, the timing of said ring and cagegears being arranged to bring said hammer against said tappet whilemoving in a direction substantially aligned with the longitudinaldireption of said tappet.

5. A device as claimed in claim 4 in which said internally toothed ringgear is mounted for rotary adjustment relative said casing to controlthe timing of said hammer, and means are provided to fix said ring gearin adjusted timing position.

ERNEST CRAIG.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

